Devtools UX: Add elements toolbar with breadcrumbs

Source/devtools/front_end/elements/elementsPanel.css

Index: Source/devtools/front_end/elements/elementsPanel.css
diff --git a/Source/devtools/front_end/elements/elementsPanel.css b/Source/devtools/front_end/elements/elementsPanel.css
index 5de02d1166923f3de206fc95a7f40369b4714abd..0bc406b3c7a70c3a6c3c9c6b7a7d7d30ea1b3c8f 100644
--- a/Source/devtools/front_end/elements/elementsPanel.css
+++ b/Source/devtools/front_end/elements/elementsPanel.css
@@ -43,6 +43,11 @@
     overflow-x: hidden;
 }
 
+.elements-topbar {
+    border-bottom: 1px solid hsla(0, 0%, 0%, 0.1);
+    flex-shrink: 0;
+}
+
 #elements-crumbs {
     flex: 0 0 19px;
     background-color: white;
@@ -52,6 +57,12 @@
     width: 100%;
 }
 
+.material #elements-crumbs {
+    flex: 1 0 28px;
+    border: none;
+    height: 100%;
+}
+
 .metrics {
     padding: 8px;
     font-size: 10px;